Cups are widely used for drinking liquids. These cups usually have an open mouth. Travel mugs and other spill-resistant cups that come with lids or caps are also known for covering the mouth to resist spillage of the cup contents. In addition, sports bottles are often provided with a screwed-on lid having a built-in straw, and a cap for sealing the end of the straw. Some of these sports bottles also have a manually operated pop-up vent which is sealed when pushed down and open when pushed up. These sports bottles still suffer from the problem that they will empty their contents if the bottle is tipped sideways, unless, fortuitously, the straw had been previously manually capped, the vent had been previously manually pushed down, and the fit between the aperture and the lid and the straw was truly sealing.
One type of commercially available cup for use by anyone, and particularly well suited for small children, includes a cup body and a lid which fits sealingly onto the cup body, with the drinking spout incorporated into the lid. Some self-sealing spill resistant cups are known and commercially available. These spill resistant cups all suffer from a variety of disadvantages.
One example of such a cup is disclosed in U.S. Pat. No. 5,079,013 to Belanger. Belanger discloses a dripless liquid container for training and feeding a young person to drink. The container of Belanger has a cup-shaped liquid housing and a lid which fits sealingly on the housing. The lid has a spout for drinking out of, with an outlet formed in the lid and in fluid communication with the spout. A spring-loaded self-sealing outlet valve is provided in fluid communication with the outlet. The lid also has an air inlet formed therein which admits air to replace the volume of fluid removed from the housing, with a spring-loaded self-sealing air rim and control valve in communication with the air inlet. The liquid container disclosed in Belanger because of the inclusion of the spring loaded valve is complicated to manufacture and assemble. The configuration of the valve also makes it difficult to clean and thus maintain sanitary conditions. Further, the cup disclosed in Belanger is relatively expensive.
Another example of a spill-resistant cup is disclosed in U.S. Pat. No. 5,890,620 to Belcastro. Belcastro improves on the liquid container disclosed in Belanger by eliminating the use of spring-loaded valves and utilizing self-sealing inlet and outlet valves which include disc shaped flexibly resilient diaphragm members. However, the drinking container disclosed in Belcastro utilizes a valve comprised of a plurality of separate and discreet parts in order to provide sufficient force on the diaphragm members to keep them from being open at all times. The use of these multiple parts provides a number of disadvantages, including increasing the cost of manufacture and assembly, as well as the time. Further, the more parts that are present, the longer a cup typically takes to clean or sanitize. Moreover, some of the valve parts are free-floating and not rigidly secured therein. If these parts move, they can affect the performance of the cup, including causing leakage, and potentially raising safety concerns.